Next tonight, we do have new surveillance as authorities hunt for a serial shooter in las Vegas. The gunman targeting several victims. ABC's Marcus Moore with the surveillance tonight. Reporter: This chilling video shows the moment a homeless man, is executed under a Las Vegas bridge. The killer opening fire on 68-year-old James Lewis. I have so many questions. And the biggest question is why. Reporter: Tonight, police desperately searching for that shooter they say is behind four separate attacks in the span of four days. Killing two people and injuring two others, three of the victims homeless. To target, the very vulnerable segment of our society, is cowardly. Reporter: Police say the spree began at 12:03 A.M. On January 29th, 45 miles north of Las Vegas. Then, at 7:13 A.M., a third man target Ed on the famous Las Vegas strip. He's found shot in the head, he manages to survive and then this horrifying surveillance video capturing critical clues, images of the suspect vehicle can. Police say he used the same gun in each shooting. Reporter: David? Marcus, thank you. When we come back here tonight, more on that new warning for Netflix users. Zwri T

This transcript has been automatically generated and may not be 100% accurate.